A few years ago, tungsten halogen technology was adapted for use in standard lamps. The new tungsten halogen standard lamps have an inner capsule that contains the tungsten halogen process, and an outer envelope that guards against possible non-passive fracture of the inner capsule, and shields the user from the high surface temperature of the inner capsule. The inner capsule is then mounted on a frame inside the outer envelope, with the frame acting as one of the electrical connections for the inner capsule. Tungsten halogen lamps can produce a higher quality light, be more efficient, and have a longer life than ordinary filamented lamps.
During assembly, the frame and inner capsule are inserted in the outer envelope, and the base is screwed on. The threaded base pinches the exterior arms of the frame against the envelope neck to make electrical contact and hold the frame in place. To make good electrical contact, and to ensure the base is not unthreaded, the frame to base contact has been made by a sharp point, aimed in the threading direction. As the base threads over the frame, the frame points dig progressively deeper into the base. In final position, the frame points are well embedded in the base, ensuring electrical contact, and are pointed against the unthreading of the base to prevent removal of the base. Because of variations in the pointed ends, the lengths of the frame components, molded glass dimensions and similar causes, the frame ends do not always contact the base equally. The frame can then be twisted in the outer envelope, leaving the inner capsule misaligned. This is a cosmetic problem. The misalignment can also be a mechanical problem. The misaligned inner capsule can knock against the outer envelope during shipment and break. The life of the inner capsule may also be affected by the irregular heat flow around the adjacent outer envelope. There is then a need for a support frame that consistently centers the inner capsule in the outer envelope.
The double envelope, tungsten halogen lamps are assembled by hand threading the base to the lamp neck. The torque characteristic of lamps with pointed frame ends is not a linear force, but is an increasing and perhaps even an accelerating force. The high torque need to thread the base to its final position may lead to injuries from repeated high stress of the assemblers, fingers, hands or wrists. By reducing the diameter of the support frame wire, the wire may be made more flexible, but a more flexible wire allows greater sway in the assembled lamp. Greater flexibility in the support frame is also likely to result in a bent, or distorted support frame. There is then a need for a double envelope electric lamp with a low assembly torque support frame for the internal capsule that is unlikely to sway or be distorted.
Standard lamps have frequently been sealed by cementing or epoxying the threaded metal base to the outer glass envelope. Fluid or paste glues and cements are not easy to work with in an assembly line operation. Inadequate gluing may occur, allowing the base to open. While excessive gluing may leave the lamps cosmetically unacceptable. Glues and cements are also usually relatively expensive materials. There is then a need for a method of coupling the metal base to the outer envelope of a capsule lamp without glue or cement.
The small portions of the threaded base have also been peened into slots formed in the lamp envelope in the past. Peening requires the lamp be properly oriented, so the peenings properly hit the preformed envelope slots. Alignment takes time, and machinery to properly execute the test. Peening regularly results in broken product, where the peening strike is excessive. Alteratively, using less peening force, yields lamps with bases that can come loose. There is then a need for a lamp with a mechanically sealed envelope and base, that does not use glue or cement.
Hand assembly of lamps does not usually lead to strong mechanical couplings between bases and envelopes. On the other hand, a lamp envelope, being made of glass is usually fragile, and a mechanical coupling made by a machine can lead to fracture of the lamp envelope, and wasted product. There is then a need for a machine made mechanical coupling between the outer envelope of a capsule lamp and a threaded metal base.
Examples of the prior art are shown by the following U.S. patents.
U.S. Pat. No. 3,194,625 issued to G. K. Danko on Jul. 13, 1965 for an Electric Lamp with Unitary inner Envelope and Stem Assembly and Manufacturing thereof shows a threaded base lamp with an internal capsule integral with an outer envelope. The threaded base is cemented to the outer envelope.
U.S Pat. No. 3,243,634 issued to F. A. Mosby on Mar. 3, 1966 for an Electric Lamp and Support Web shows a threaded base lamp with an internal capsule supported from the threaded base. The threaded base is cemented to the outer envelope with an epoxy.
U.S. Pat. No. 4,647,809 issued to R. G. Blaisdell et al. Mar. 3, 1987 for Electric Lamp with Self Mounting Frame Assembly and Method of Constructing Same, shows a threaded base lamp with an internal capsule. The internal capsule is supported on a wire frame that was spiked ends bent around the opening of the outer envelope. The threaded base is threaded to the outer envelope causing the spiked ends to be compressed and pointed into the base. The spikes then resist unthreading of the base from the outer envelope.
U.S. Pat. No. 4,959,583 issued to Vito J. Arsens et al on Sep. 25, 1990 for a Reflective Lamps Having An Improved Light Source Mounting Arrangement shows a threaded base lamp with an internal capsule. The threaded base is coupled to the outer envelope a high temperature resistive adhesive.